1. Field of the Invention
This invention relates to brakes and, more particularly, to brakes having multiple actuators that enable either more responsive control of braking torque or an increase in braking torque.
2. Disclosure of Related Art
Conventional brakes typically employ a single actuator for setting or releasing the brake. However, the use of a single actuator to either set or release the brake has drawbacks.
In brakes that use a single actuator to release the brake, the actuator is responsible for both releasing the brake (i.e., overcoming the setting force of the springs or other means for setting the brake) and controlling braking torque. Because control of the braking torque is not independent of the brake release, however, control of the braking torque becomes a function of both the force exerted by the actuator and the force exerted by the springs or other means for setting the brake. As a result, the ability of a user to control the braking torque through use of the actuator is somewhat limited.
In brakes that use a single actuator to set the brake, the use of a single actuator limits the braking torque that can be generated. In a conventional disc brake, for example, the brake discs are aligned along an axis. The actuator exerts a force along that axis to compress the brake discs and set the brake. The axial force exerted by the actuator, however, is limited by the radial surface area on which it acts, and, therefore, by the diameter of the brake. The braking torque is proportionately limited.
There is thus a need for a brake that will minimize or eliminate one or more of the above-mentioned deficiencies.